A typical high power, radio frequency (RF) semiconductor device may include one or more input leads, one or more output leads, one or more transistors, wirebond arrays coupling the input lead(s) to the transistor(s), and wirebond arrays coupling the transistor(s) to the output lead(s). The wirebond arrays have significant inductances at high frequencies, and such inductances may be factored into the design of input and output circuits for a device (e.g., impedance matching circuits).
In some cases, input and output circuits may be contained within the same package that contains the device's transistor(s). More specifically, an in-package, input impedance matching circuit may be coupled between a device's input lead and a control terminal (e.g., the gate) of a transistor, and an in-package, output impedance matching circuit may be coupled between a current conducting terminal (e.g., the drain) of a transistor and a device's output lead. Each of the input and output circuits may include one or more capacitive elements, along with the inductances inherent in the wirebond arrays interconnecting the capacitive elements with the device's transistor(s) and with the input and output leads.
Wirebond arrays may be designed to function as inductors with relatively high Q (quality) factors, which is desirable to achieve high efficiency amplifiers. However, wirebond arrays often lead to undesirable inductive coupling between various device components. Further, the inclusion of such wirebond arrays in RF devices mandates the use of relatively complex back-end assembly processes using expensive equipment that is not commonly used in the semiconductor industry. For example, the wirebond array attachment equipment must be configured to accurately shape and space each wirebond in order to achieve desired inductances. The inductive coupling characteristics and back-end assembly costs associated with the inclusion of wirebond arrays in RF amplifier devices detrimentally affects device performance and cost.